Starlight Instruments Single Red Beam 2" Laser Collimator - 635nm
- Single red beam operates at 635nm for twilight use.
- The Howie Glatter Laser Collimator incorporates a solid state laser diode that does not fade or change with time and use.
- Factory-aligned to 15 arc-seconds providing 0.1 inch accuracy at a distance of 20 feet,
- The Howie Glatter Laser Collimator is shock resistant to keep its alignment - even when dropped.
- Includes 123A lithium battery, 1mm aperture stop, case, collimation rings and instructions.
Inside the collimator is a solid-state laser diode, which emits an
intense laser beam through a front aperture, exactly along the central
axis of the cylindrical collimator body. The beam acts as a "reference
line" from which alignments are made. For a laser collimator it is of
supreme importance that the beam be aligned with the collimator's
cylindrical axis, for if it is not, the resultant "alignment" of the
telescope optics will be off-center and asymmetric, and the telescope
will produce aberrated images.
"When I started manufacturing laser collimators I realized that in order
to produce consistent and accurate results they must be highly
resistant to mechanical shock, so that internal laser alignment is
maintained. I experimented with this aspect of collimator construction
and developed a design which tremendously increased shock resistance.
After aligning the laser within 15 arc seconds, I shock test each
collimator by whacking it against a block of urethane plastic (urethane
prevents marring), striking it at least a dozen times on three axis. I
then recheck the laser alignment, and if it has not changed the
collimator passes. I believe this is the most important difference
setting my collimator apart from all others I know of. They will
withstand a shock equivalent to dropping from eyepiece position, up the
ladder on a big Dob, without alteration of laser alignment."
The beam from all red diode lasers used in collimators is fuzzy-edged
and elliptical in cross-section. When collimating, you sometimes must
judge the location of the center of the spot by eye. To improve
collimating precision, all of my collimators (except 532nm) are supplied
with a removable accessory plastic aperture stop having a 1mm hole,
which push-fits into the laser aperture. It produces a tiny, circular
beam impact which allows more accurate alignment. With the holographic
collimators, it is not used at the same time as the optional holographic
feature, and the diffractor must be removed to install the stop. With
the stop inserted the beam impact at a distance of one meter or more
looks like a star diffraction pattern, with a central dot surrounded by
diffraction rings. The surrounding rings can help in centering the beam
very accurately.
I offer the red holographic collimators with a choice of either 650
nanometer or 635nm wavelength. The two lasers have the same radiometric
power output, but because the human eye's sensitivity to the shorter
wavelength is greater, the 635nm. laser appears about two or three times
brighter. The higher cost of 635nm laser diodes increases the
collimator price, but it enables optional holographic collimation in
brighter ambient light. If you intend to collimate in early twilight, it
is a good choice. In darkness, however, the 650nm laser is quite
adequate. Because single beam collimators concentrate all the laser
light in the central beam, the 650nm laser is quite adequate for them."
Precise... Accurate... and Durable... What more could you ask?
